Energy Recovery System

ABSTRACT

An apparatus and method for recovering thermal energy from boiler stack exhaust gases and using the thermal energy in biomaterial processing. The apparatus and method include means to improve the boiler&#39;s operation and reduce emission of certain regulated compounds.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/404,833 filed Mar. 16, 2009 and entitled “Energy Recovery System,”which claims benefit of U.S. Provisional Application Ser. No. 61/036,488filed on Mar. 14, 2008, entitled “Energy Recovery System” which ishereby incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of energy recovery. Morespecifically, the invention relates to a method of recovering andrecycling thermal energy from industrial and utility boilerapplications.

2. Background of the Invention

Ethanol-based fuel production and industrial fermentation processes relyheavily upon the conversion of food crops to fuel or other chemicals.Corn, sugar beets, sugarcane, and other crops are regularly used assources of starch or sugar. Implementation of crop-based feedstocks forethanol fuels has negative implications in the global food stocks.Additionally, the temperate climate zones where these crops areprimarily grown undergo seasonal changes that prevent the year roundregular production of ethanol fuel demanded by industry andtransportation.

Cellulose is a major structural component of nearly every plant, makingit one of the most abundant molecules on the planet. Biomacromolecularcellulose consists of glucose monomers. Algin is a structuralpolysaccharide in the cell walls of marine plants. The biomacromoleculealgin consists of D-mannuronate epimers. Furthermore, as aplant-produced material, both are easily renewable resources that do notrequire starch or sugar-rich food crops. The capacity to break them downinto monomers yields an extensive supply of sugars for ethanol, otherfermentation or other chemical syntheses. The primary difficulty withcellulose and algin is that it is difficult to hydrolyze to obtain thesugar monomers because the polymer is protected by a number of otherbiomaterials.

Hydrolytic techniques currently exist to hydrolyze cellulose to producesugars. However, available technologies require costly physical plantsand the infrastructure to operate them. The significant capitalexpenditure is a strong incentive for the avoidance of a company'sinvestment in new plants or technologies for the exclusive production offuel grade ethanol by processing of plant-based biomaterial. Further,the power supply industry is facing strict regulations on emissionsproduced from the burning of fossil fuels. Power plants are beingrequired to add components and facilities such as treatment facilities,filters, heat exchangers, stack scrubbers, and energy capturingcomponents to remove certain waste products and recycle energy releasedby the system. These additional facilities and components are requiredto lower the nitrogen oxide, sulfur, and mercury emissions to meet newregulations.

Power plant systems typically include boilers to produce steam for theprocess of the power plant system and often the waste heat from theboilers is lost and not recovered or recycled for reuse in the powerplant system or other related process system. Consequently, there is aneed for the recovery and recycling of the thermal energy from theburning of fossil fuels in the power plant system and using that thermalenergy for the processing of biomaterials.

BRIEF SUMMARY

A method of operating a thermal recycling system includes transportingthermal energy and products from a boiler, a cooker and a bioreactorthrough the system whereby the thermal energy from the boiler is used toprocess biomaterial, and thermal energy from biological processes isused to preheat combustion air. The method also reduces emissions andrecovers heat by returning gases from the biomaterial processing to theboiler. This is accomplished utilizing low level heat from bioprocessesand other sources to humidify combustion air, then taking advantage ofthe additional humidity supplied by products of combustion and/or fuelassociated water to dehumidify the stack gas by a comparable amount butat a higher temperature. The temperature difference betweenhumidification and dehumidification is sufficient to allow a heatexchanger to transfer the heat of dehumidification to the incomingcombustion air. Condensate from dehumidification of stack gas is usuallyacidic and may be used for neutralization or for dilute acid hydrolysisor pretreatment of cellulose and/or algin.

A boiler energy recycling system comprises a boiler, a cooker, abioreactor, a combustion air preheater and a water treatment facility.The hot gases from the boiler are directed to the cooker and warmedcombustion air is directed to the bioreactor, the cooker for pulping orotherwise favorably altering the properties of the biomaterial and thebioreactor for aerobically, or anaerobically treating biomaterial. Thewater treatment facility treats the water flowing into the boiler andprovides its wastewater to the cooker. The water treatment facility canalso produce treated water for the cooker or for other purposes.

The foregoing has outlined rather broadly the features and technicaladvantages of the invention in order that the detailed description ofthe invention that follows may be better understood. Additional featuresand advantages of the invention will be described hereinafter that formthe subject of the claims of the invention. It should be appreciated bythose skilled in the art that the conception and the specificembodiments disclosed may be readily utilized as a basis for modifyingor designing other structures for carrying out the same purposes of theinvention. It should also be realized by those skilled in the art thatsuch equivalent constructions do not depart from the spirit and scope ofthe invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of theinvention, reference will now be made to the accompanying drawings inwhich:

FIG. 1 is a schematic illustrating an embodiment of an energy recoveryand recycling system;

FIG. 2 is a thermal energy flow diagram according to an embodiment of anenergy recovery and recycling system;

FIG. 3 is an acidic liquid flow schematic according to an embodiment ofan energy recovery and recycling system;

FIG. 4 is a basic liquid flow schematic according to an embodiment of anenergy recovery and recycling system;

FIG. 5 is an illustration for transporting and agitating biomaterial;

FIG. 6 a conventional boiler material flow diagram;

FIG. 7 is a material flow diagram of an example of an energy recoverysystem with an open composting system; and

FIG. 8A is a material flow diagram according to an example of an energyrecovery system with demineralized feedwater.

FIG. 8B is a material flow diagram according to an example of an energyrecovery system with demineralized feedwater.

DETAILED DESCRIPTION

FIG. 1 is a schematic illustrating an embodiment of an energy recoveryand recycling system 10. Energy recovery and recycling system 10comprises a stack gas system 20 having a boiler 22 with a burner 24 thatproduces a stack gas 26 that supplies thermal energy, via a conduit 28,to a biomaterial cooker facility 30 and a composter 40 of a bioreactor50. Bioreactor 50 may also comprise a biomaterial separator 70 andfermenter 80. The energy recovery and recycling system 10 is asupplemental system to a conventional boiler 22 application used inanother plant process. The boiler may create steam or thermal energy forsuch other processes. Additionally, the boiler operation wastewater maybe used in other processes.

The water flowing through the tubes of boiler 22 is heated by burner 24that combusts a hydrocarbon or fossil fuel such as natural gas, coal, oroil from feed 84 mixed with a combustion air from feed 82. The stack gassystem 20 may further include an air blower 86 which introduces thecombustion air feed 82 into burner 24. The flue gas produced by burner24 exits an outlet 12 of boiler 22 that is connected to a first stack32. A boiler water-treatment facility 60 may provide water treated toremove inorganic and metallic contaminants from the boiler feedwater forthe boiler 22.

A damper 34 positioned within stack 32 reversibly closes stack 32 to thepassage of flue gases 26 a through stack 32. Damper 34 serves to directthe remainder of the stack gases 26 into conduit 28. In furtherapplications, the damper 34 improves safety of the stack duringmaintenance and startup. Conduit 28 passes adjacent to biomaterialcooker facility 30 and passes through composter 40. Conduit 28 releasesstack gas 26 b through a second stack 36 to the environment.

Biomaterial cooker facility 30 is located in proximity to boiler 22along and/or adjacent to conduit 28. Biomaterial cooker facility 30 maybe a widening or a broadening in the conduit 28. Biomaterial cookerfacility 30 cooks ligno-cellulose rich biomaterial and/or algin richbiomaterial at high temperature. Biomaterial cooker facility comprises avessel 38 for holding the biomass under high temperature and may bemoveable within cooker facility 30 relative to stack gas conduit 28whereby the temperature within the vessel 38 may be regulated by theproximity of vessel 38 to the stack gas conduit 28. In stationary cookerembodiments, dampers may be located in conduit 28 to direct and routegas to and from cooker facility 30 as a means to regulate temperature invessel 38. Vessel 38 further comprises at least one vent 42 for removingand directing gases resulting from the cooking of biomass to conduit 44.Composter 40 includes an inlet 46 in communication with vent 42 ofvessel 38. In alternative embodiments, biomaterial cooker facility 30and composter 40 are located in the same building and on opposite sidesof gas conduit 28.

Bioreactor 50 comprises composter 40, biomaterial separator 70, andfermenter 80. In embodiments, composter 40 and separator 70 areconstructed as portions of the same building. Bioreactor 50 comprises atleast one air intake system 52 having a fan 54 for blowing airover/through biomaterial separator 70 and the composter 40. Bioreactor50 comprises at least one outlet 48 for withdrawing the heated air fromthe bioreactor and communicates with composter gas conduit 76 intoblower feed conduit 78 to produce a combustion air stream 82 returningit to burner 22. Outlet 48 is preferably located in composter 40 andconfigured to maintain an air pressure inside composter 40 such that itis at least below ambient pressure.

Composter 40 is constructed as a heat exchanger for the removal of heatfrom gas conduit 28 to heat aerobically composting biomaterial.Composter 40 is configured as a generally open room facility with stackgas conduit 28 running substantially therethrough. Composter 40 can beopen to the environment at one end. The walls of composter 40 arethermally insulated and corrosion resistant. For example, the walls ofcomposter 40 may be constructed of materials such as glass, ceramic orplastic. Composter 40 may include at least one industrial or commercialgarage bay 56 configured to permit hoppers, trucks, rail cars, or othersimilar transportation vehicles access to the interior of the composter40.

The composter 40 serves the purpose of making a useful product fromlignin and other portions of the biomass not contained in the desiredprimary cooker product. These portions do not remain with the pulp orother desired cooker product, nor degrade in the fermenter 80. Composterfeed may include additional biomaterials such as, but not limited to,residential yard waste, commercial crop processing waste or commercialbuilding site plant clearings. Furthermore, any biomass rejected fromthe cooker feed for oversize, undersize, excess associated dirt or anyother reason will be transported to the composter 40. Composting is theaerobic decomposition of organic matter. Heat from gas conduit 28 isfavorable for the organisms responsible for the process of composting.Additionally, hot vapors from the vessel 38 are passed into thecomposter 40. The process of composting produces some volatile, organicgas. This composter gas 76 includes water vapor, methane, andnitrogenous gases. Additionally, during heating of compost in composter40, the gas conduit 28 may cool below the dew point of some vapors inthe gas. The condensate supplements the water and may be used to balancethe alkalinity in the fermenter 80. In other embodiments condensate fromthe gas conduit 28 may be used for acidic cooking liquor or the diluteacid hydrolysis of biomass when the fossil fuel fired includes a sulfurcomponent. Condensate exits from the gas conduit 28 at outlet 58 and isdrained to anaerobic fermenter 80. The biomaterial separator 70 may be aportion of composter 40. The biomaterial separator 70 comprises aseparation facility for the product stream 62 of biomaterial cookerfacility 30. Solid biomaterial leftover from cooking in biomaterialcooker facility 30 is hereinafter referred to as pulp. The liquid thebiomaterial heated in the biomaterial cooker facility 30 is referred toas cooking liquor. However, one skilled in the art will recognize thatmany potential cooker applications result in additional solid or liquidproducts. Product stream 62 includes pulp and cooking liquor.

The biomaterial separator 70 separates the pulp from the cooking liquorby flowing the product stream 62 over a solid/liquid separation deviceknown to those skilled in the art. Additional products, if any, may beseparated as well. The liquid and finely divided solid portion notrecovered with the pulp flows into a drain 64. Cooking liquor frombiomaterial separator 70 flows through drain 64 and into conduit 66connected to fermenter 80 for fermenting. Pulp from separator 70 may betransported offsite for ethanol or other fermentation. On site, the pulpmay be transported by a biomaterial vessel conduit 68 or other means tocomposter 40 for bio-processing. The bio-processing steps may comprisefungal pretreatment or enzyme production. In some embodiments, thevapors from the biomaterial separator are passed through the composter40 to heat and humidify the combustion air. The cooking liquor isdirected through outlet 66 into fermenter 80.

Fermenter 80 may be a conventional fermenter known by one skilled in theart for fermenting a liquid having dissolved biomaterials. In certainembodiments, fermenter 80 is an anaerobic methane fermenter. Fermenter80 receives cooking liquor from bioreactor 50 and condensate from stackgas conduit 28 through outlet 58 for processing. Fermenter 80 producesgases and water. The fermenter gases are recycled to boiler 22 byconduit 72 and the water is drained to a water treatment facility 90 forremoving biomaterial contaminants.

The fermenter 80 breaks down the biomaterial suspended in the cookingliquor and condensate without oxygen. Fermentation may create a methaneand volatile organic gas mixture. This fermenter gas from fermentationof the cooking liquor is removed from fermenter 80 via fermenter gasoutlet 74 to gas conduit 72. Fermenter gas conduit 72 communicates withcomposter gas conduit 76 into blower feed conduit 78 to produce acombustion air stream 82. Combustion air stream 82 may be transportedvia blower 86.

Further waste compounds may be removed from the liquid from separationfacility 70 and fermenter 80 by any means known to one of skill in theart. In embodiments, the liquid is drained from fermenter 80 to atreatment facility 90. The water treatment facility 90 may comprise anyknown to one skilled in the art. In certain embodiments, water treatmentfacility 90 is a trickling filter. A trickling filter acts as anattached growth bioreactor and a settler to remove organic compoundsfrom water. In energy recovery system 10, water treatment facility 90releases water of sufficient purity to discharge. In some arrangementsof the system, the purified water from water treatment facility 90 maybe returned to boiler 22, but preferably to biomaterial cooker facility30, and/or fermenter 80 and/or composter 40 to make up for water lostduring operation.

To supplement fossil fuel feed 84 and to provide oxygen, composter gasesconduit 76 from composter 40 and fermenter gases conduit 72 are routedto blower 86. Blower gases 82 are combined with fossil fuel feed 84 toreduce emissions of certain regulated gases upon combustion. Compostergases 76 and fermenter gases 72 are high in volatile organic compoundsand water vapor. In embodiments, increased volatile organic compounds inthe combustion air reduce fossil fuel consumption. Fossil fuelconsumption is also reduced by increased water vapor in stack gas 26 bwhich increases its dew point resulting in more heat transfer intocomposter 40 out of duct 28 resulting in higher temperature and loweroxygen concentration in ducts 76, 78, and 82, while emissions of oxidesof nitrogen (NOx) are reduced.

Water treatment facility 90 is configured to treat the waste liquids andproduce clean water. Water treatment facility 90 may compriseconventional systems or devices without limitation as known to oneskilled in the art. In embodiments, the water treatment facility 90comprises at least a trickling filter. Typically a trickling filter isan attached growth bioreactor and a settler for removing organiccompounds from water. Filtration and other treatment may occur such thatwater is of sufficient purity to be discharged.

Energy recovery system 10 utilizes waste heat from the stack gases 26 ofstack gas system 20 for preparing biomaterial for composting, enzymeproduction and/or fermentation. Additionally, by-products of boileroperation are used to generate acidic and/or alkaline chemicals forpreparing the biomaterials for enzyme production or fermentation. Heatand combustible by-products from the composting, enzyme productionand/or fermentation process, such as volatile organics, dust, moldspores, and/or flying insects, are utilized to reduce fossil fuelconsumption by increasing the temperature and amount of fuel incombustion air feed 82 from air blower 86. Non-combustible by-productsof the composting, enzyme production and/or fermentation process areutilized to reduce emissions by reducing the oxygen content of thecombustion air, leading to lower maximum flame temperature and lower NOxcontents in the stack gas. The lowered temperature of stack gases 26 bwould cause corrosive damage to boiler 22 or boiler stack 32 were thesestack gasses not contained in duct 28 and stack 36, constructed ofcorrosion resistant materials known to those skilled in the art.

The temperature of the stack gases in boiler applications is betweenabout 350° F. and about 700° F., preferably between about 400° F. andabout 500° F., and the velocity is from about 5 ft/s to about 50 ft/s.These parameters will vary depending on operating conditions as is knownto one skilled in the art. Under typical operating conditions, the heatnot recovered from the stack gas is typically released to theenvironment via stack 32. The burning of the hydrocarbon fuels in burner24 to heat water in boiler 22 produces stack gases 26 a. Burner 24 burnsthe fossil fuel from feed 84 and the combustion air from feed 82. Theproperties of the combustion air impacts the stack gases 26 a, includingtemperature, humidity, density, and emissions of monitored compounds,such as oxides of nitrogen (NOx), released to the environment.Additionally, the stack gases 26 a contain acidic compounds that wouldbe corrosive to the boiler 22 and boiler stack 32 if they condensed toliquid.

As a result of continued operation, boiler 22 requires extra fuel tominimize condensation of the corrosive components in exhaust gases.Boiler water treatment 60 provides water to boiler 22 and further addsbasic or alkaline chemicals to the feed water conduit 95 to minimizecorrosion in the steam and or hot water piping. After extendedoperation, boiler 22 begins to collect solid particulate matter andwaste compounds on the waterside of boiler tubes. This material and itsprecursors, contained in blowdown liquid, are removed from boiler 22 tomaintain operational efficiency by blowdown conduit 92. Due toconditions within boiler 22, the compounds contained in the blowdown aretypically alkaline. The blowdown liquid may be neutralized in typicaloperations by adding acidic compounds from the water treatment facility60 or adding purchased acid by treatment conduit 94 so that the blowdownliquid can be treated and released. Treatment conduit 94 empties intoblowdown treatment conduit 96, which feeds the basic watertreatment/storage facility 98. The wastewater generally resultant fromboiler operation may be considered boiler operation wastewater.

In energy recovery system 10, the blowdown liquid may be combined withwastewater from the water treatment facility 60 from conduit 94 and theresulting stream in blowdown treatment conduit 96 are introduced tobasic water treatment/storage facility 98. Treated basic water stream istransported by conduit 99 to cooking vessel 38 to make up for cookingliquor lost during the biomaterial cooker process.

In addition to controlling emissions and reducing corrosion, the heatenergy in the stack gases is recovered for additional processes byenergy recovery system 10. FIG. 2 illustrates a flow diagram of anembodiment of gas cycle 100 in energy recovery system 10 whereby thermalenergy in the boiler stack gas conduit 128 is recovered and recycled. Inboiler 122, water is heated to boiling by burning hydrocarbon fuels.Rather than being released to the environment, the heat from hightemperature boiler gas conduit 128 is cycled to a biomaterial cookerfacility 130. Biomaterial cooker facility 130 acts to exchange the heatfrom high temperature boiler gas conduit 128 to cook the biomaterials.Biomaterial cooker facility 130 utilizes the high temperature to furtherthe dissolution of biomaterial into cellulose, hemi-cellulose, andlignin.

From biomaterial cooker facility 130, hot gases in conduit 144 aretransported to bioreactor 150. In embodiments, bioreactor 150 comprisescomposters, fermenters, and/or other processes that utilize bacteria,fungi, enzymes or multi-cellular organisms to break down, digest, oralter biomaterial. The units of bioreactor 150 further act as heatexchanger whereby the hot gases exchange heat with the biomaterials.Heating biomaterials, undergoing aerobic composting and anaerobicfermentation is advantageous for the release of organic volatile gasesand water vapor. Bioreactor gas conduit 176 exits bioreactor 150 at anelevated temperature, advantageous for introduction as combustion airinto burner 122. Bioreactor gas conduit 176 may be combined withfermenter gas and introduced to burner 122 via blower 186. The heatedbioreactor-gases in conduit 176 are mixed with combustion air or fuel inblower 186 for burner gas feed 182. The temperature and humidity iselevated in burner gas feed 182, thus reducing the emissions produced inboiler 122.

In certain embodiments, the hot gas conduit 144 may leak into thebioreactor facility as a means to recycle stack gases. It isadvantageous to recycle some of the hot gases as means to further reduceNOx emissions. Additionally, this method may reduce costs to constructthe bioreactor 150.

Referring now to FIG. 3, an embodiment of an acidic cooking liquor watercycle 200 for energy recovery system 10. Feed water conduit 395 toboiler 324 is de-mineralized by boiler water treatment 360. Boiler waterdemineralizer 360 uses acidic chemicals like hydrochloric or sulfuricacid and basic chemicals like caustic soda and/or caustic potash toregenerate ion exchange resins for demineralization. An acidicwastewater stream 359 and a basic wastewater stream 394 result. Theacidic wastewater stream 359 is combined with the acidic condensate 358from gas conduit 328. Gas conduit 328 exhausts combustion products fromboiler 324 to stack 326 through bioreactor 350. A portion of thechemicals from demineralizer regeneration are highly acidic. Thechemicals from condensation in the stack may also be highly acidic ifthe fuel fired in boiler 324 contains sulfur. The combined acidicstreams 358 and 359 are stored in acidic water treatment/storagefacility 357. Conduit 356A routes this acidic water to biomaterialcooker facility 330 via conduit 399. Biomaterial cooker facility 330heats cellulose containing biomaterial in a solution, or cooking liquor.Heating the cooking liquor dissolves the lignin hemicellulose and leavesthe cellulose unsolubilized. Biomaterial outlet stream 362 entersbioreactor 350, comprising, for example, composter 340 and fermenter380. The remaining cellulose, hereinafter called pulp, is strained fromthe cooking liquor in bioreactor 350. The de-lignified cellulosic pulpis used for further processes such as but not limited to: ethanol orother fermentation, enzyme production, animal feed, biofuel, or otherapplications as known to one skilled in the art.

Although demineralizing removes many minerals, salts and other chemicalsfrom the boiler feed water in conduit 395, residual compounds remain. Asthe water boils within boiler 324, the concentrations of these materialsincrease, reducing the efficiency of boiler 324. In order to return tooptimum efficiency, these materials are removed and in blowdown viaconduit 392. The residual compounds are stored with basic wastewaterfrom conduit 394 originating in demineralizer 360 in the basic watertreatment/storage facility 398. The basic water stream from watertreatment/storage facility 398 is routed to fermenter 380 via conduit337B. In certain embodiments, bioreactor 350 comprises composter 340 andfermenter 380. In further embodiments, bioreactor cooking liquor isdrained from composter 340 to fermenter 380 by conduit 366.

Referring now to FIG. 4, an embodiment of a basic cooking liquor watercycle 200 for energy recovery system 10. Feed water conduit 395 toboiler 324 is de-mineralized by boiler water treatment 360. Boiler watertreatment 360 uses acidic chemicals like hydrochloric or sulfuric acidand basic chemicals like caustic soda and/or caustic potash toregenerate ion exchange resins for demineralization. An acidicwastewater stream 359 and a basic wastewater stream 394 result. Theacidic wastewater stream 359 is combined with the acidic condensate 358from gas conduit 328. Gas conduit 328 exhausts combustion products fromboiler 324 to stack 326. The combined acidic streams 358 and 359 arestored in acidic water treatment facility 357.

Although demineralizing removes many minerals, salts and other chemicalsfrom the boiler feed water in conduit 395, residual compounds remain. Asthe water boils within boiler 324, the concentrations of these materialsincrease, reducing the efficiency of boiler 324. In order to return tooptimum efficiency, these materials are removed and in blowdown viaconduit 392. The residual materials may be stored along with basicwastewater from conduit 394 originating in demineralizer 360 in thebasic water treatment/storage facility 398. The caustic chemicals fromion exchange resin regeneration and the use of basic chemicals toprotect the boiler and associated lines from corrosion leaves the basicwater treatment facility 398 in conduit 337B as a highly basic liquidmixture. This basic water is routed to biomaterial cooker facility 330via conduit 399.

Biomaterial cooker facility 330 heats cellulose containing biomaterialin a solution, or cooking liquor, to dissolve the lignin and leave thecellulose unsolubilized. In certain basic cooking liquor embodiments,the nitrogenous-basic compounds concentrations in the cooking liquor aresupplemented by the addition of lime or potash to both supply additionalbase for cooking liquor and improve compost quality. Biomaterial outletstream 362 enters bioreactor 350, comprising, for example, composter 340and fermenter 380. The remaining cellulose, hereinafter called pulp, isstrained from the cooking liquor in bioreactor 350. The de-lignifiedcellulosic pulp is used for further processes such as but not limited toethanol or other fermentation, enzyme production, animal feed, biofuels,or other applications as known to one skilled in the art.

The cooking liquor within 362 has a high nitrogen content resulting fromcorrosion inhibitors in the boiler blowdown and from cooking thebiomaterial. The high nitrogen content is advantageous for manyprocesses within bioreactor 350 such as but no limited to, compostingand fermenting. In certain embodiments, bioreactor 350 comprisescomposter 340 and fermenter 380. In further embodiments, bioreactorcooking liquor is drained from composter 340 to fermenter 380 by conduit366. The cooking liquor may combine with the acidic water stream fromconduit 356A draining acidic water treatment facility 357.

In either acid or basic cooking liquor applications, waste water fromfermenter 380 is removed by conduit 385 to water treatment facility 390.Water treatment facility 390 treats the waste water for biologicalmaterial and removal of organic compounds. In some embodiments, watertreatment facility 390 comprises a trickling filter and treats the wastewater in preparation for release as water of sufficient purity todischarge. Alternatively, water treatment facility 390 removes organicmaterial as sludge from waste water. In further embodiments the sludgemay be returned to the fermenter 380. Water treatment facility 390 alsohumidifies the air surrounding filters and treatment apparatuses. Thehumid air from water treatment facility 390 may be returned to boiler324 in the combustion air feed 378 for reducing regulated emissions.

Water may be routed to alternative facilities as a means to regulate thehumidity of the processes conducted therein. In these embodiments, thewater in biomaterial cooker 330 is sourced from boiler blowdowntreatment 398, boiler water treatment 360, water treatment facility 390and/or condensate from stack gas conduit 328. In further embodiments thehot water in the cooking liquor from biomaterial cooker facility 330 mayadditionally be used to produce steam, and to condense this steam towater for treatment in water treatment facility 390. Further, water forfermenter 380 may be sourced from boiler 324 feed water excesses. Waterfrom fermenter 380 may be routed (not shown in Figures) to composter 340to increase the moisture and nitrogen in the biomaterial as needed.

Referring again to FIG. 1 In further alternative embodiments, thecooking liquor for pulping in biomaterial cooker facility 30 may beprovided from biofuel waste products. The biofuel waste byproducts suchas glycerol, methanol, butanol, and spent enzymes, monobasic and dibasicacids are feasible additives for the heated delignification ofcellulose. Further, the spent catalyst utilized in fatty acid esterbiofuel production mixed with the soda or potash is envisioned as acomponent of the cooking liquor, in some embodiments.

In further alternative embodiments, the cooking liquor for biomaterialcooker facility 30 may be provided from boiler operation wastewater. Thewastewater may be derived from solid fuel handling waste products.Storage of coal or peat or other solid fuels results in fuel pilerunoff, the water-soluble components of which are known to those skilledin the art to promote the hydrolysis of lignin. Acid mine drainagepotentially available to power plants located near mines is also apromoter. Additionally in cold weather, the contents of fuel piles aresometimes treated with antifreeze components such as glycols, known tothose skilled in the art both to promote the hydrolysis of lignin and tosolubilize the resulting hydrolysis products. These antifreezecomponents are contained in runoff. Also most solid fuels contain ashprecursors. Collection of ash sometimes involves contacting ash withwater. This contacting makes available the water-soluble portions of theash to promote the hydrolysis of lignin. Any of these aqueous streamsare envisioned as a component of the cooking liquor, in someembodiments.

Referring to FIG. 5, in another embodiment, vessel 438 is a commercialbiomass transport to move biomass into, out of, or about the energyrecovery and recycling system 10. A trailer, or rail car attachment arepotential examples of commercial transports to move biomaterial aboutthe energy recovery and recycling system 10. For example, thebiomaterial may be transported from the biomaterial cooker facility 430to the biomaterial separator 470. In further applications, vessel 438may be transported to a commercial garage bay 456 of composter 440. Itcan be envisioned that a ceiling-mounted lift system 483 removes andsuspends the vessel 438 above the transporter 481 from the ceiling ofthe composter 440. In order to distribute heat through the biomasscontained therein, an agitator 491 may be employed to agitate thecontents of vessel 438 after the tractor-trailer 456 is driven out fromunder vessel 438. Alternatively, the lift system 481 may agitate thecompost. Furthermore, agitation of the biomass prevents caking along thewalls of vessel 438. In certain embodiments, vessel 438 comprises anagitator 491 disposed within said vessel; the internal agitator may acton the compost by mixing, turning, stirring and/or other actions. Vessel438 may further serve to transport compost to burner 424 and boiler 422for fuel.

The following examples are provided to further illustrate variousembodiments of the present invention.

EXAMPLES

In the following examples, all gas rates are in SCF (standard cubicfeet) per stream hour unless otherwise noted, and all liquid and solidrates are in lbs per stream hour unless otherwise noted. The flue gassystem has 10 MM BTU/H (Million British Thermal Units per Hour) fuelfired with 15% excess combustion air having an ambient humidity of 100%at 70° F. The stack gas exits from the flue gas system at a temperatureof substantially 460° F., unless otherwise noted.

Illustrated in FIG. 6 is a conventional boiler application, withoutbiomaterial incorporation for recovery and recycling. Illustrated inFIGS. 6 and 7 are specific embodiments of an energy recycling systemwith biomaterial treatment and bioreactor facilities for the productionof pulp and compost.

Example Calculations 1 Conventional Boiler System

In a standard boiler system illustrated in FIG. 6, the calculations forgaseous fossil fuel flow and oxygen mixture are 10 MMBtu/H*1000 Btu/SCF(Btu per standard cubic foot)=10000 SCF/H (standard cubic feet per hour)of fuel gas. @2 volumes O2 per volume fuel gas=20000 SCFH O2 arerequired. @4.762 volumes air per volume O2 plus excess Air@15%, 109526DSCF/H (dry standard cubic feet per hour) air are required.

Adding relative humidity to the air, at 70° F. and 100% relativehumidity, moisture is equal to 0.0158 lbs H2O per lb. dry air. In otherunits, moist air is comprised of 1 lb. dry air=13.35 CF (cubic feet) dryair and of 0.34 CF H2O=0.0158 lbs H2O. This composition is equivalent to13.69 CF of moist air weighing 1.01 lbs. The burner feed is thus 109526DSCF/H Air+2781.64 SCF (standard cubic feet) H2O. This humid air is fedto the burner along with 10000 SCF/H (standard cubic feet per hour) offuel gas. Enthalpy of the humid air is 34.09 Btu/lb dry air=301611.42Btu/H, calculated using 359 SCF per lb mole and 29 as MW (molecularweight) of air.

After combustion, the stack contains 10,000 SCF/H CO2 and 22781.64 SCF/HH2O and 86526 CF/H Atm Nitrogen and 3000 CF/H O2 totaling 122307.64CF/H. The stack contains 22781.64 SCF/H water in 122307.64 total SCF/Hwhich provides a flue gas composition of 0.23 moles water per mole drygas. This composition is equivalent to 0.14 lbs H2O per lb dry air for adew point of 137° F. This 137° F. dew point forms the design goal forthe exit temperature of the high temperature side of a heat exchanger,the low temperature side of which contains biological material. Anywater vaporized in the low temperature side will be condensed in thehigh temperature side if this goal is met. This cycle maximizes theutilization of the biologically derived heat. Much of this biologicalheat vaporizes water, present in large amounts during biologicalprocesses from biological necessity. The heat of vaporization of thiswater is recovered for preheating combustion air in the process of thisinvention.

Example Calculations 2 Energy Recycled Via Biomaterial and Bioreactors

Using biomass in the flue gas system alters the material and energybalances and the water usage. Below is an heat transfer calculationusing the equation Q=UA(ΔT).

Extremophile bacteria in composting do well between 70° F. and 158° F.,therefore assume the average temperature of 70° F.+158° F./2=114° F. tobe the low temperature side of a biomaterial heat exchanger. The stacktemperature as set forth above is 460° F. The average high sidetemperature can be assumed to be 298.5° F. because the high sidetemperature decreases down to 137° F. from 460° F. The average ΔT is298.5° F.−114° F.=184.5° F. Typical tubular heat exchangers have heattransfer coefficients, U, of 10 to 50 with air on the shell side and 5to 20 with air on the tube side.

Window glass has a heat transfer coefficient, U, of about 1.2 atstandard conditions which are at low temperature, no wind, and nocondensation. Radiant heat varies as the fourth power of the temperatureand its contribution to the U rises quickly with temperature. Use 3.1for the heat transfer coefficient, Q. The heat flow for an exchanger inthe stack above going from 460° F. to 137° F. is 808130.51 Btu/H.

Solving for A in Q=UA(ΔT), The area of the heat exchanger/composter is1412.94 square feet. This is less than the surface area of a buildingneeded for composting 1 MM Btu/H of biomass. Such a building roughed outbelow is a 44100 gallon tank. If diameter D equals height, H=19.5 feet,the outside area of a tank this size is 1792.436 square feet. So adouble walled building containing the same volume as the tank would belarge enough to furnish the calculated heat exchanger area.

To calculate the heat of Combustion or heat of Bacterial Metabolism ofbiomass use publised values for Bagasse, which is sugarcane pulp, and isprimarily composed of carbohydrates. As an example for a burner, usingthe carbohydrate formula CH₂O, gives a molecular weight, MW, of 30. Theuse of the molecular weight of monomeric carbohydrate creates verylittle error when calculating the combustion stoicheometry of polymericcarbohydrates, like bagasse. Bagasse combustion produces 8000 Btu/lb, ona dry basis. So, 1 MMBtu/H requires 125 lb/Hr of dry bagasse. Using theMW of 30, 4.17 moles/hr O₂ are required. At 359 SCF per mole, the O₂required=1495.83 SCFH O₂. At 4.76 volumes of air per volume O₂ inatmospheric air, the air required is 8191.63 DCF/H air. Enthalpy is34.09 Btu/lb dry air=22558.02 Btu/H.

Flue Gas from the above calculation contains 1495.83 CF/H CO₂, 1703.87CF/H H₂O and 6471.42CF/H Atmospheric Nitrogen and 224.375 CFH O₂ with15% excess air. The total flue gas is 9895.508815 CFH.

In the system, the biological zone replaces flue gas recirculation, andthe assumption is made that the dry basis heat capacities of air andflue gas are the same. The error in this assumption is about 3.0%, basedon the approximation that all heat is quenched by water. Quenched bywater is the same thing as saying all temperature rises result in 100%relative humidity. This approximation is justified by the large amountsof water known to be present because water is required to supportbacterial life.

Fifteen percent (15%) is a poor (low air) assumption for in-vesselcomposting excess air, as is saturation equilibrium between water andair. Particularly since, if plant matter did not preferentially absorbwater life would not exist. It is thought that the combination of thesetwo bad assumptions will result in a good assumption based on billionsof years of evolution requiring it to be good. If it weren't, therewould be an excess of partially decayed fern trees not eaten bydinosaurs. Another way of justifying the combination these two poorassumptions is that in the adiabatic system of this invention thebiological heat will get to the boiler in some combination of hotter airwith increased moisture content. For economics purposes in thecondensing air preheater system of this invention it really doesn'tmatter much exactly what this combination is.

Proceeding with the 1 MM Btu/H of biomass calculation, the dry basisincoming air plus flue gas from biological material is: 117717.63CF/H=9509.22 lbs/hr. Enthalpy is 1324169.44 Btu/H or 139.25 Btu/lb whichputs the temperature at 125° F.; At 125° F. and water saturation, watercontent increases the total volume of 1 lb of dry air plus water to 17cubic feet. Dry air alone is 14.73 CF per lb of dry air. The differenceof 17−14.73=2.27 cubic feet of water weighs 0.095 lbs. The humid airthus contains 0.095 lbs. H₂O per lb dry air.

Incoming O₂ in the combustible mixture in the burner is 17.09% percent.This is near ideal for flue gas recirculation. A 23.5%, basis incomingair, flue gas recirculation would achieve the same O₂ percentage of 17%.A 21.00%, basis incoming air, flue gas recirculation would achieve thesame temperature: 125.54 or 125° F. assuming 460° F. stack temperature.However steam generation would of course be higher with the biomass. Ifthe biomass is 50% water, then 6000 pounds per day would be required,however biomass is and must be much wetter than this. In this example,water flows out of the biological zone at 903.38 lbs per hour. Water inis 139.47 lbs per hour from incoming air+85.43 lbs/hr from oxidation.The difference between 903.38 lbs per hour of water leaving and(85.43+139.47)=224.9 lbs. per hour of water available from other sourcesis the amount of water evaporated from the biomass, which is 678.48 lbsper hour. Dry basis biomass is 125 lbs/hr, meaning the biomass musteither contain initially 84% water or be contacted later with makeupwater if it is dryer than 84%. The 678.48 lbs per hour of waterevaporated from the 1 MMBtu per hour of incoming biomass can beexpressed as 0.68 lbs water per MBtu of biomass combusted or oxidized.

Another source of heat, which will also cause water to evaporate is heatinput through the exchanger. 808130.51 Btu/H, a number derived inexample 1 from calculating the heat exchanger with no biomass, gives anenthalpy of 1109742 Btu/H leaving the heat exchanger. This enthalpy is125.43 Btu per lb dry air.

The resulting temperature is 122° F., which at saturation gives 14.66 CFdry Air and 2.03 CF of H₂O. This totals 16.6 CF of humid Air containing18.44% O₂. Water is used at the rate of 622.35 lbs per hour which can beexpressed as 0.77 lbs H₂O per Mbtu of heat exchanged. Repeating thisheat exchanger calculation for 1 MM Btu/H transferred gives 1301611.42Btu/H Enthalpy leaving the heat exchanger. This enthalpy is 147.12Btu/Lb dry air at a temperature of 128° F. with an O₂ content of 17.99%.This compares to an oxygen content of 17.09% for the same number of Btufrom oxidation of biomass. So one comparison is that 1000 Btu of Heattransfer is as good at reducing the oxygen content of the incoming airas is 771.72 Btu of biomass oxidation. This same estimation techniquefor the 808130.51 BtuH of heat transfer yields the result that 1000 Btuof heat transfer and is as good as 810.66 Btu of oxidation for reducingthe oxygen content of the incoming air.

Using 800 Btu of heat transferred as equivalent to 1000 Btu of biomassoxidation for reducing incoming air oxygen content as an engineeringapproximation for comparing indirect heat transfer to oxidation ofbiomass, conventional composting with a 49 day residence time wouldrequire an inventory of 294000 lbs which at 50 lbs per CF would occupy5880 CF=44100 gal. That amount could be handled in a reasonably sizedtank or airtight enclosed building. This size would be greatly reducedif the compost were consolidated as its volume shrank. In-vesselcomposting can take 7 to 14 days because of better air contacting andtemperature control. In-vessel composting is preferable, especially ifthe agricultural operation which produces the biomass will take back itscompost, because the compost so returned does not have to be completelystabilized.

To compare the size of potential water sources, boiler blowdown at 4cycles and 1000 Btu/lb heat of vaporization and 90% condensate return is250 lbs/H=719.42 gal/day compared to approximately 900 gal/day neededbased on 6000 lbs/Day of 50% water biomass. This is close. Adding theregeneration caustic water would not increase the water volume much. Aprovision can be made for recycle of some trickling filter water tosmooth out operations and for tank storage of blowdown and regenerationwater until needed. Cooling tower blowdown condensing the boiler's steamgenerated at 70% efficiency assuming 3 cycles of concentration in thecooling tower is 2333.33 lbs/H, which is plenty of water.

TABLE 1 Enthalpy Balance around the boiler. (FIG. 6) Enthalpy BalanceMMBtu/H IN OUT 1.49 FEEDWATER 0.10 BLOWDOWN 9.56 STEAM 0.97 STACK 9.56FUEL(LHV) 0.41 LOSS 11.05 11.05 TOTAL

TABLE 2 Enthalpy Considerations. (FIG. 7) expressed in lbs of steam forconsistent units Enthalpy Considerations lbs steam/H EVAPORATED incomposter 938 CONDENSED water in exchanger 712 COOLED OFF gas inexchanger 741 INCREASED STEAM MAKE from boiler 514 ASSUME half of thisincreased STEAM MAKE is lost 257

TABLE 3 Enthalpy fates. (FIG. 7) USED 2576849 Btu Biofuel SAVED 1408968Btu Fossil Fuel Produced 128884.9 Btu PULP Produced 320276 Btu Compost

TABLE 4 Enthalpy Balance. (FIG. 8A and 8B) Enthalpy Balance MMBtu/H INOUT 1.44 FEEDWATER 0.01 BLOWDOWN 9.56 STEAM 0.17 STACK 0.45 BIOSOLIDSHEAT OF COMB 8.66 FUEL(LHV) 0.82 LOSS 0.00 T.F PURGE WATER 0.01 WASHWATER 10.56 10.57 TOTAL Fuel saved is about 9% of the fired duty.

TABLE 5 Fermenter Water Balance Calculations: Anaerobic MethaneFermenter. (FIG. 8A and 8B) FERMENTER WATER BALANCE IN OUT 394 SPENTLIQUOR 48 ACID CONDENSATE 342 A.M.F. UNDERFLOW 166 A.M.F. OVERFLOW 67T.F. BIOSOLIDS 1 BIOGAS 509 509 TOTAL

TABLE 6 Heat Exchanger Water Balance Calculations. (FIG. 8A and 8B) HEATEX WATER BALANCE IN OUT 408 COMPOST FEED 143 HUMIDIFIED AIR 42 COOKERVENT 1 BIOGAS 34 COMPOST REACTION 627 FAN THROUGHPUT 627 627 TOTAL

While the preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theembodiments described and the examples provided herein are exemplaryonly, and are not intended to be limiting. Many variations andmodifications of the invention disclosed herein are possible and arewithin the scope of the invention. Accordingly, the scope of protectionis not limited by the description set out above, but is only limited bythe claims which follow, that scope including all equivalents of thesubject matter of the claims.

1-25. (canceled)
 26. A thermal energy recovery system, comprising aboiler having a burner configured to produce thermal gases comprisingsteam and exhaust, wherein the burner has an inlet configured to supplyair to the burner; a cooker configured to cook biomaterial in liquid; abioreactor including an anaerobic fermenter component and an aerobiccomposter component; a thermal gas conduit extending from the boilerthrough the cooker and the bioreactor; and a thermal liquid conduitconfigured to recover liquid by-products from the boiler and the thermalgas conduit, wherein the thermal liquid conduit is configured to directan acidic portion of the liquid by-products to the cooker and direct abasic portion of the liquid by-products to the bioreactor.
 27. Thesystem of claim 26, further comprising a solids conduit extendingbetween the cooker and the bioreactor.
 28. The system of claim 27,wherein the bioreactor further comprises a separator configured toseparate solid and liquid biomaterial, wherein the aerobic compostercomponent is configured to process the solid biomaterial and theanaerobic fermenter component is configured to process the liquidbiomaterial.
 29. The system of claim 26, wherein the bioreactor furthercomprises at least one component chosen from the group consisting of abiomaterial shredder, a biomaterial hydrolytic vessel, a biomaterialpulper, a fungal pretreater, an enzyme synthesis reactor, and adigester.
 30. The system of claim 26, wherein the bioreactor is a heatexchanger in thermal communication with the thermal gas conduit and theair supplied to the inlet.
 31. The system of claim 30, wherein thebioreactor is a condenser configured to remove water from the boilerthermal gases by cooling them and heat the air in the inlet.
 32. Thesystem of claim 30, wherein the bioreactor is a humidifier configured tohumidify the air in the inlet.
 33. The system of claim 26, furthercomprising at least one wastewater treatment facility in fluidcommunication with the thermal liquid conduit.
 34. The system of claim33, wherein the at least one water treatment facility is chosen from thegroup consisting of a demineralizer, a wastewater treater, a tricklingfilter, and combinations thereof.
 35. The system of claim 26, whereinthe thermal gas conduit comprises dampers configured to block thermalgases from entering at least one component of the system chosen fromgroup consisting of the cooker, the bioreactor, and the inlet.
 36. Thesystem of claim 26, wherein the thermal gas conduit is configured tocarry gaseous biofuel waste byproducts.
 37. The system of claim 26,wherein the thermal liquid conduit is configured to carry liquid biofuelwaste byproducts.
 38. A container for transporting biomaterial,comprising: at least one vessel configured to retain biomaterial,wherein the at least one vessel is reversibly attach to a transportationvehicle; a sealable open top configured to provide access to theinterior of the vessel for depositing biomaterial; an agitator disposedin the interior of the vessel, wherein the agitator is configured toagitate the biomaterial in the at least one vessel; and a liftconfigured to lift the vessel from the transportation vehicle.
 39. Thecontainer of claim 13, wherein the agitator comprises an apparatusconfigured to aerate the biomaterial.